1. Technical Field
The present invention relates in general to air craft engines and, in particular, to an improved system, method, and apparatus for a diverterless hypersonic inlet for integrated turbojet and ram-scramjet aircraft jet engine applications.
2. Description of the Related Art
Boundary layer diverters using splitter plate and wedge geometries are traditionally employed to reduce or eliminate boundary layer thickness upstream from the inlets of airbreathing propulsion systems at Mach 1 to Mach 2+. The high drag and weight of such devices has been overcome in the past with more thrust (which required bigger engines), more engines, or the additional use of afterburners. These designs result in yet more weight, less vehicle payload capacity, higher fuel consumption, and/or other aircraft design penalties. Higher Mach number, multi-engine aircraft (Mach 2 to 3+) have employed efficient, axisymmetric spike inlets or underwing-mounted nacelles. However, these designs require large amounts of internal boundary layer bleed, add significant drag, and are structurally inefficient.
The development of the ramjet or scramjet powered hypersonic aircraft has been historically thwarted by inefficient inlet and forebody designs. An inefficient hypersonic forebody and inlet design can have poor transonic performance characteristics, which compromises the ability of an on-board gas turbine propulsion system to accelerate to ramjet transition speed without running out of fuel. An inefficient design can also allow ramjet ingestion of a thick boundary layer which delays ramjet startup until the vehicle achieves at least Mach 3.5. Gas turbine propulsion systems are historically inefficient beyond Mach 2.5, so afterburning, base burning, rocket assistance, releasing the vehicle from an aircraft at altitude, and combinations thereof are generally considered to fill the gap between Mach 2.5 and 3.5, and thereby achieve required ramjet start-up conditions. As such, the problems associated with hypersonic inlets (boundary layer flow, high transonic drag, etc.) have not been resolved to facilitate the practical use of efficient, self-powered, hypersonic airbreathing vehicles. An improved solution that addresses these limitations would be desirable.